I will present recent results from numerical-relativity simulations studying the impact of finite-temperature effects in binary neutron star mergers with microphysical equations of state and realistic neutrino transport. Through systematic modifications to the effective nucleon masses, it is possible to increase the specific heat of the equation of state, which leads to colder, more compact remnants due to reduced thermal pressure support. A full Bayesian analysis demonstrates that this effect will be measurable in the postmerger gravitational wave signal with next-generation observatories at signal-to-noise ratios of 15. I will also show that the neutrino treatment leads to qualitative differences in the postmerger evolution, illustrating the need for a proper treatment of the optically thick regime when considering thermal effects.